1. Field of the Invention
The invention relates to a drive system for escalators and pedestrian conveyors. More specifically, the invention related to a drive system for escalators and pedestrian conveyors having at least one driving chain.
2. Related Art
Generally known are so called escalators and pedestrian conveyors, which are intended for indoor use, for example in department stores or the like. Such escalators and pedestrian conveyors are provided with driving chains, in which, with regard to the relatively low forces, the step or pallet bolts including the rollers, which cooperate with the steps or pallets, are positioned in the respective joint areas of the driving chains.
Also known are heavy load escalators, which are used outdoors, for example in underground shafts or the like. In heavy load escalators, roller chains are usually used as driving elements, the step rolls being provided outside the driving chain in view of the bigger dimensioned drives. The constructional effort in a heavy load escalator is much higher than for a department store escalator, whereby also the total width of the heavy load escalator has to be greater than for a department store escalator.
Therefore it would be desirable to provide measures to manufacture and run a heavy load escalator with a constructional effort, which is nearly as low as the one of a department store escalator.
DE-A 1756813 describes a roller-step-chain connection of escalators in which the step bolt is provided between two joints of the driving chain. The rollers are preferably provided between two joints of the driving chain inside or outside the inner plates or outer plates. These two selectable possibilities can be used for a department store escalator (roller placed inside) on the one hand, and for a heavy load escalator (roller placed outside) on the other hand.